JSFiddle - React, Tailwind, and code Playground

by ktstowell

HTML

<h1><a href="http://projecteuler.net/problem=3">Problem:</a></h1>
<p>The prime factors of 13195 are 5, 7, 13 and 29.</p>
<p>What is the largest prime factor of the number 600851475143 ?</p>
<hr />
<div id="prime"></div>

JavaScript

(function() {
    var //cap = 600851475143,
        cap = 131950,
        chunk = 1000,
        prime_cont = document.getElementById('prime'),
        i = cap,
        j;
    
    // First get the block size to process. Handling the
    
    
    // Second, find each prime number, top down, 
    // lower than the cap.
    function main() {
        console.log(i)
        var count = chunk; 
        while(count-- && i > 0) {
            if(isPrime(i)) {
                if(isFactor(i)) {
                    prime_cont.textContent = 'The largest Prime Factor is: ' + i;
                    i=0;
                } else {
                    i--;
                }
            } else {
                i--;
            }
        }
        
        if(i>0) {
            setTimeout(main, 1);
        }
    }
    
    function isPrime(n) {
        var ret;
        
        for(j=n; j>0; j--) {
            if(n % j === 0 && j !== n && j !== 1) {
                ret = false;
                break;
            } else {
                ret = true;
            }
        }
        
        return ret;
    }
    
    function isFactor(n) {
        if(cap % n === 0) {
            return true;        
        }
    }
})(document);